title: Characterization of lower-limbs inter-segment coordination during the take-off extension in ski jumping.
abstract: Take-off, the most important phase in ski jumping, has been primarily studied in terms of spatio-temporal parameters; little is known about its motor control aspects. This study aims to assess the inter-segment coordination of the shank-thigh and thigh-sacrum pairs using the continuous relative phase (CRP). In total 87 jumps were recorded from 33 athletes with an inertial sensor-based system. The CRP curves indicated that the thighs lead the shanks during the first part of take-off extension and that the shanks rotated faster at the take-off extension end. The thighs and sacrum first rotated synchronously, with the sacrum then taking lead, with finally the thighs rotating faster. Five characteristic features were extracted from the CRP and their relationship with jump length was tested. Three features of the shank-thigh pair and one of the thigh-sacrum pair reported a significant association with jump length. It was observed that athletes who achieved longer jumps had their thighs leading their shanks during a longer time, with these athletes also having a more symmetric movement between thighs and sacrum. This study shows that inter-segment coordination during the take-off extension is related to performance and further studies are necessary to contrast its importance with other ski jumping aspects.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Movement Analysis and Measurement (LMAM), Lausanne, Switzerland. Electronic address: julien.chardonnens@epfl.ch.
authors.forename: Julien
authors.initials: J
authors.lastname: Chardonnens
authors.forename: Julien
authors.initials: J
authors.lastname: Favre
authors.forename: Florian
authors.initials: F
authors.lastname: Cuendet
authors.forename: Gérald
authors.initials: G
authors.lastname: Gremion
authors.forename: Kamiar
authors.initials: K
authors.lastname: Aminian
mesh_terms: D000054:Acceleration; D000293:Adolescent; D001076:Aptitude / Q000502:physiology; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011214:Practice, Psychological; D011597:Psychomotor Performance / Q000502:physiology*; D012447:Sacrum / Q000502:physiology; D012865:Skiing / Q000502:physiology*; D013848:Thigh / Q000502:physiology; D055815:Young Adult
keywords: 2330; Continuous relative phase; Coordination; Inertial sensors; Motor control; Ski jumping; Take-off